Knowledge of flame-wall interaction helps in the understanding of flame phenomena near a wall and of flame extinction. In the present work different flame characteristics were measured in square, narrow quenching channels. A propane/air mixture was employed and direct visualization was used to observe flame behavior under quenching conditions. Flame propagation velocity was determined during downward propagation. As expected, close to quenching condition it was found to be lower than that under adiabatic conditions and close to the values predicted by the quenching theory. The dead space appeared to be larger for rich mixtures than that found with lean ones. Flame curvature reached its maximum value for stoichiometric mixtures decreased for both leaner and richer mixtures. Numerical simulation revealed the structure of limit flames during their propagation in quenching channels. It was confirmed that flame quenching depends on the relation between heat release rate and heat loss rate.